Maneuvering robotic vehicles having a positionable sensor head

ABSTRACT

Configurations are provided for vehicular robots or other vehicles to provide shifting of their centers of gravity for enhanced obstacle navigation. Various head and neck morphologies are provided to allow positioning for various poses such as a stowed pose, observation poses, and inspection poses. Neck extension and actuator module designs are provided to implement various head and neck morphologies. Robot control network circuitry is also provided.

CROSS REFERENCE TO RELATED APPLICATIONS

This U.S. patent application is a continuation of, and claims priorityunder 35 U.S.C. §120 from U.S. patent application Ser. No. 12/652,478,filed Jan. 5, 2010 now U.S. Pat. No. 8,079,432, which is a continuationof U.S. patent application Ser. No. 11/842,868, filed on Aug. 21, 2007now U.S. Pat. No. 7,654,348, which claims priority under 35 U.S.C.§119(e) to U.S. Provisional Application 60/883,731, filed on Jan. 5,2007, and U.S. Provisional Application Ser. No. 60/828,611, filed onOct. 6, 2006. The disclosures of these prior applications are consideredpart of the disclosure of this application and are hereby incorporatedby reference in their entireties.

STATEMENT AS TO FEDERALLY SPONSORED RESEARCH

This invention was made in part with Government support under contractDAAE07-03-9-F001 awarded by the Technical Support Working Group of theDepartment of Defense. The Government may have certain rights in theinvention.

TECHNICAL FIELD

This invention relates to robotics, and more particularly to mobilerobots or vehicles capable of climbing by shifting their center ofgravity.

BACKGROUND

Robots are useful in a variety of civilian, military, and lawenforcement applications. For instance, some robots may inspect orsearch buildings with structural damage caused by earthquakes, floods,or hurricanes, or inspect buildings or outdoor sites contaminated withradiation, biological agents such as viruses or bacteria, or chemicalspills. Some robots carry appropriate sensor systems for inspection orsearch tasks. Robots designed for military applications may performoperations that are deemed too dangerous for soldiers. For instance, therobot can be used to leverage the effectiveness of a human “pointman.”Law enforcement applications include reconnaissance, surveillance, bombdisposal and security patrols.

Small, man-portable robots are useful for many applications. Often,robots need to climb stairs or other obstacles. Generally, a small robotmust span at least three stair corners to climb stairs effectively, andmust have a: center of gravity in a central disposition to maintainclimbing stability. When the size or length of a. robot reaches acertain small size relative to the obstacle or stair it must climb, therobot's center of gravity usually has a deleterious effect on climbingability. What is needed, therefore, is a robot design that can climbobstacles that are large relative to the size of the robot.

Such robots are also employed for applications that require a robot toinspect under and around various objects and surfaces. What is needed,therefore, are robot sensor heads moveable in various degrees offreedom.

SUMMARY

Various robot head and neck morphologies are provided to allowpositioning for various poses such as a stowed pose, observation poses,and inspection poses. Neck extension and actuator module designs areprovided to implement various head and neck morphologies. Robot actuatorcontrol network circuitry is also provided.

One preferred embodiment is a robot including a chassis having a centralopen volume, a steerable drive supporting the chassis, and neckextension movable he coupled to the chassis, and a pan link extensionhaving proximal and distal ends being coupled to the neck extension atthe proximal end with a first tilt access actuator. The pan linkextension has a one axis actuator along its length. A sensor head iscoupled to a distal end of the pan link extension. The sensor head asmovable using the axes.

Preferred actuator designs provide and actuator module, the moduleincluding the actuator motor, control circuitry for the motor, a slipring and having multiple concentric conductive traces which matched tocorresponding contacts on an electrical contact board rotateable withrespect to the slip ring.

Configurations arc provided for vehicular robots or other vehicles toprovide shifting of their center of gravity for enhanced obstaclenavigation. In preferred embodiments, a robot chassis with articulateddriven flippers has an articulated neck and articulated sensor headmounted toward the front of the chassis. The articulated neck is pivotedforward to shift he vehicle combined center of gravity (combined CO)forward for various climbing and navigation tasks. Flippers may also beemployed with the CG shifting effect of moving flippers added to that ofthe pivoting head and neck. Various embodiments may have differentweight distributions to allow different CG shifting capabilities.

One preferred embodiment includes a chassis supporting a skid steereddrive and having a leading end, a trailing end, and a chassis center ofgravity (chassis CG) therebetween, a set of driven flippers, anarticulated neck and an articulated sensor head the chassis, set offlippers, neck, and articulated sensor head adapted to move and therebyproduce a corresponding adjustment in the vehicle center of gravity.Such adjustment may be employed to allow stair climbing, obstaclenavigation, crevasse navigation, or other desired operations. Thearticulated neck may include a pan axis element.

Robots according to various morphologies may be positioned in variousposes suitable to accomplish their mission. A preferred control schemeprovides preset poses in response to certain operator commands. PresetCG shifting poses and preset observation or inspection poses areprovided.

The details of one or more embodiments of the invention are set forth inthe accompanying drawings and the description below. Other features,objects, and advantages of the invention will be apparent from thedescription and drawings, and from the claims.

DESCRIPTION OF DRAWINGS

FIG. 1 shows robot with extendable arms or flippers.

FIG. 2 depicts one method by which a robot may climb stairs.

FIG. 3 shows another exemplar tracked vehicle robot.

FIG. 4 depicts another tracked robot vehicle.

FIG. 5 depicts a side representation of another robot.

FIG. 6 depicts a robot vehicle encountering an obstacle under twodifferent scenarios.

FIG. 7 depicts a robot vehicle having flippers residing within thelength of the vehicle.

FIG. 8 depicts a robot using flippers to mount an obstacle backwards.

FIG. 9 shows and example of how a pivotable neck and sensor headcontribute significant CG shifting ability.

FIG. 10 depicts elevated neck positions for two configurations.

FIG. 11 depicts a robot in various positions crossing a crevasse.

FIG. 12 depicts another robot CG shifting technique.

FIG. 13 is a flow chart of a method of ascending an obstacle.

FIG. 14 shows a robot having a wheel drive.

FIG. 15 depicts a robot in a stowed configuration.

FIG. 16 depicts a perspective view of another robot vehicle.

FIG. 17 depicts the robot of FIG. 16 in a climbing configuration.

FIG. 18 depicts another robot in a stair climbing position with aforward-shifted combined CG

FIG. 19 depicts another robot in a stair descending position. In thisconfiguration the robot has chassis pointing downward.

FIG. 20 depicts a robot climbing an obstacle forward.

FIG. 21 shows a robot mounting an obstacle backwards.

FIG. 22 shows a robot with a four degree of freedom system forpositioning a sensor head.

FIG. 23 shows a robot with four degrees of freedom and a “pan-link”section for positioning a head.

FIG. 24 shows a robot that implements a possible four degree of freedomsystem for positioning a head employing another joint morphology.

FIG. 25 shows another robot that implements a possible four degree offreedom system for positioning a head employing another jointmorphology.

FIG. 26 shows another robot that implements a possible four degree offreedom system for positioning a head using a joint morphology thatincludes a 45-degree link.

FIG. 27 illustrates a possible configuration of a preferred design for aneck extension and actuator assembly.

FIG. 28 illustrates a cutaway view of a possible embodiment of theactuator assembly of FIG. 27.

FIG. 29 depicts a cutaway view of a possible embodiment of a first tiltaxis of the actuator assembly of FIG. 27.

FIG. 30 depicts another cutaway view of a possible embodiment of a firsttilt axis 30 of the actuator assembly of FIG. 27.

FIG. 31 depicts yet another cutaway view of a possible embodiment of afirst tilt axis of the actuator assembly of FIG. 27.

FIG. 32 illustrates a cutaway view of a possible embodiment of a secondtilt axis of the actuator assembly of FIG. 27.

FIG. 33 illustrates a cutaway view of a possible embodiment of a neckattachment or “shoulder” axis of the actuator assembly of FIG. 27.

FIG. 34 illustrates another cutaway view of a possible embodiment of aneck attachment or “shoulder” axis of the actuator assembly of FIG. 27.

FIG. 35A depicts an exploded perspective view of a neck extensionconnector.

FIG. 35B depicts another exploded perspective view of a neck extensionconnector.

FIG. 35C depicts a perspective view of an assembled and latched neckextension connector.

FIG. 36 illustrates a block diagram of a robot sensor head.

FIG. 37 illustrates a block diagram of a robot neck tilt module.

FIG. 38 illustrates a block diagram of a robot neck pan module.

FIG. 39 illustrates a block diagram of a robot neck attachment tiltmodule.

FIG. 40 illustrates a block diagram of circuit components in robotchassis or base.

FIG. 41 shows a robot using an extended pan-link section in a lowprofile pose.

FIG. 42 shows a robot in a pose for looking through windows.

FIG. 43 shows a robot in a pose for observing underneath its supportingsurface.

FIG. 44 shows a robot in a pose for looking around a corner.

FIG. 45 shows a robot in an alternate low profile pose.

FIG. 46 shows a robot in an under vehicle self inspection pose.

FIG. 47 shows a robot in another self inspection pose.

FIG. 48 shows a robot in a high profile observation pose.

FIG. 49 shows a robot in a pose for inspecting under low obstacles.

FIG. 50 depicts a flow chart for moving to preset positions.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION

Various tracked robotic vehicles have been developed that are thesubject of, for example, U.S. Pat. Nos. 6,431,296, 6,263,989, 6,668,951and 6,651,885. These patents are instructive on the construction oftracked robotic vehicles having driven flippers, and means ofarticulation of robotic components, and are hereby incorporated byreference in their entirety into this application. Other robotic vehicledetails and features combinable with those described herein may be foundin a U.S. Provisional application, filed Oct. 6, 2006, and assigned Ser.No. 60/828,606, the entire contents of which are hereby incorporated byreference.

FIG. 1 shows robot 100 with extendable arms or flippers 130. The armsare shown fully extended configuration in which forward arms 130 extendbeyond the front of main body 140. The combination of forward tracks 120and main tracks 110 and provide an extended length base. Main body 140includes a vertically symmetrical rigid frame 310, which includesparallel vertical side plates 312. Side plates 312 are rigidly coupledby tubes 320, 322, and an articulator shaft 330. The rigid componentsare designed for strength and low weight and are preferably made from amaterial such as 7075-T6 aluminum. Alternative versions of the robot canuse other materials, such as other lightweight metals, polymers, orcomposite materials.

Alternative versions of the robot can use other types of tracks, such astracks made up of discrete elements. However, debris may be caughtbetween elements and such tracks are generally heavier than flexiblebelts. Other flexible materials can also be used for continuous belttracks. Referring back to FIG. 1, in this embodiment, each front track120 is narrower but otherwise similar to main tracks 110, having groovesand a V-shaped segment on the inside surface, and soft cleats 350attached to the outside surface. A front drive pulley 344 drives eachfront track 120. Each front drive pulley 344 is toothed and has acentral V-shaped channel that loosely mates with the V-shaped rib on theinside of the corresponding front track 120. On each side, front drivepulley 344 is coaxial with main drive pulley 342, and both drive pulleyson a particular side turn in unison on a common axle. A smaller smoothsurfaced front idler puller 346, which also has a V-shaped channel,supports each front track 120 at the extreme end of the correspondingarm 130.

As depicted in FIG. 1, front tracks 120 are supported by arm side plates332 using front track supports 334. Front track supports 334 arewedge-shaped and each has a series of angled slots similar to those inmain track supports 314. The arm side plates 332 on each side of therobot are rigidly coupled to one another through articulator shaft 330,and therefore move together.

Other designs may be employed to produce a robot with such a skidsteered drive and driven flippers. For example, some embodiments mayemploy techniques taught in the various U.S. patents that areincorporated by reference herein.

FIG. 2 depicts one method by which robot 100 may climb stairs. Thedepicted robot 100 can raise arms 130 in order to mount an obstacle,such as a stair 1010, in its path. To mount the first step of staircase1010, robot 100 raises its arms 130 and drives forward to raise its maintracks 110 onto the first stair. The robot then assumes a fully extendedmode thereby extending its wheelbase to increase it stability and toprovide as smooth a ride a possible up the stairs. Cleats (not shown inFIG. 2) provide mechanical locking with the stair edge needed to drivethe robot up the stairs.

One embodiment of the robot 100 may be specifically dimensioned to climbcommon stairs, with step dimensions of up to a 17.8 cm (7-inch) rise and27.9 cm (11-inch) tread. As the robot tilts or inclines, the verticalprojection of the center of gravity (CG) with respect to the groundmoves backwards. For stable travel on stairs, the extended wheel base ofthe main and forward tracks in the fully extended mode span a minimum oftwo steps (i.e. at least 66.2 cm for 17.8 cm by 27.9 cm stairs) suchthat the vehicle is supported by at least two stair treads at all times.Note that the depicted robot 100 can climb larger stairs for which itcannot span two steps, but the traverse will not be as smooth as therobot will bob with each step.

To avoid nosing up or down (pitch instability) while climbing stairs,the vertical projections of the center of gravity is located in a stablerange which is at least one step span (i.e., 33.1 cm (13 inches) for17.8 cm by 27.9 cm stairs) in front of the furthest rear main trackground contact 160 and at least one step span behind the front mostfront track ground contact 180.

Alternative versions of the robot can use shorter track dimensions thatdo not satisfy the requirement of spanning two steps. Without furthermodifications, however, the center of gravity can be outside the stablerange. Such robots may not be as stable on stairs, although inertialeffects add to dynamic stability at increased velocities, smoothing thetraverse on stairs. Various methodologies may be used to mitigate thisand other climbing and terrain traversing problems. Below we describedifferent embodiments (having different morphologies) for a basic smalltracked vehicle system that may have enhanced capability to climb ortraverse.

FIG. 3 shows an exemplar tracked vehicle robot. The depicted system isprimarily comprised of four parts: 1) a main tracked vehicle chassis301, 2) a “flipper” tracks 302 on one end of the vehicle, 3) a sensorhead 303 preferably containing drive cameras and other sensors 304, and4) a neck mechanism 305 that connects head 303 to chassis 301, Manyimproved robotic vehicle designs may be derivative of this basicplatform design. Various designs may be required to carry variouspayloads such as sensors, transmission equipment, or robotic tools, forexample.

The tracked vehicle robot may be required to surmount a variety ofobstacles that will require the vehicle center of gravity (CG) to fallwithin a certain range. These obstacles include, for example, stairs,single vertical steps, and slopes. Included herein are tracked-vehiclemorphology capable of meeting these “primary” requirements. Becausetracked vehicle robots may be subject to both stringent overall weightand stowed size requirements, it is desirable to be able to negotiatethese obstacles with the smallest sized vehicle possible such that theseconstraints can be met as well. To do this reliably, it is alsodesirable to achieve all of this with the simplest system possible.Likewise, power consumption of the drive train must be considered tomeet varied endurance requirements. Further, the system may be requiredto elevate the drive sensors 304 to a specific height which may play animportant factor is being able to shift the CG to be able to negotiateextreme obstacles.

A typical such obstacle is the ability to climb standard stairs with7-inch risers by 11-inch landings, for climbing higher obstacles.Climbing slopes is sometimes required. These requirements typically needto be met while minimizing weight, and size for portability, maximizingvehicle endurance, and accommodating extra payloads for certainscenarios. Some small tracked vehicle robots require a minimum drivesensor height above the ground to see over obstacles.

FIG. 4 depicts another tracked robot vehicle. In this example, neck 305is attached to chassis centrally, rather than to a vertical wall of thetrack drive (FIG. 3). The actuator motor 306 in is shown mounted tochassis 301, but may also be provided in a flush housing or othermounting arrangement. Actuator 306 may be powerful enough to move neckand head designs with significant mass for center of gravity shifting(CG shifting) or other applications. Neck. 305 may also be provided withtapped holes or other fittings to attach various payloads. Neck 305 mayalso be relatively much larger in diameter than depicted to provide forhousing various components or payloads. Actuators may be backdriveableor non-backdriveable, which may depend on the types of tasks desired forneck 305. Further, while track-driven robots are shown, other drivemeans may be used such as wheels. Closely spaced or overlapping treadedwheels may be used to provide mobility and climbing capability similarto that of a track drive. Such variations typically encompass the maindrive, while preferred flippers use tracks. The flipper and chassistrack systems maybe compliant tracks or rigid sectional tracks.

Depicted in FIG. 4 is a payload storage opening in chassis 301. For“head-forward” embodiments such as those in FIG. 3 and FIG. 4, payloadstorage is preferably at or toward the front of chassis 301. Preferablysuch storage resides close to the center of the track footprint so asnot to adversely affect CG shifting capability as described herein.Payloads may of course also be housed in the track housings on bothsides of the chassis, and in or on the neck and head. In someembodiments chassis 301 is configured as depicted with a payload deck,and others may have different structures. Chassis 301 may be providedwith tapped holes to accept cargo attachment or fixture attachment.Chassis 301 may also be provided with stowage space or a slot for neck305 to stow into while in a stowed position such as, for example, P5depicted in FIG. 9. Head 303 may also be provided with a slot andrecessed articulation joint to lower the profile of the head and neck instowed position. To protect the head, it must stow as much as possiblewithin the profile of the tracks. In one preferred embodiment, the-headwill approximately be at least 1.5 inches thick; likewise, the neck andits pan/tilt actuators will probably require at least another 1.5 inchesunder the head when stowed. Since the track wheel pitch diameter will bearound 5 inches, and a typical flipper torque tube will be about 0.75inch diameter (delivering torque from a flipper actuator), this onlyleaves a little over 2 inches for the head and neck to stow. Therefore,it will probably not be possible for the head to stow both over thetorque tube and remain within the track volume.

Chassis 301 is preferably constructed of strong lightweight materials,and may include a shell around an enclosed volume. A structural volumehousing electronics may also support the necessary load paths of thesystem. In the simplest case where the chassis is modeled as a hollowbox, there is adequate strength to also support wheels and running gearon the sides of this box.

Some characteristics for three different embodiments are describedbelow. Note that the values depicted are for one possible morphology andthat other morphologies can be derived by reallocating weights from onecomponent to another. For example, in typical examples the flippers willbe about 10% of the total robot weight. To provide heavier flippers (sayby moving the batteries to the flippers), the battery weight (which istypically around 23% but may vary greatly) would be subtracted out ofthe chassis and added to the flippers, thus making the flippers containabout 33% of the total robot weight. Further, partial battery capacitymay be shifted to the robot head for a heavier head providing, in somedesigns, an improved CG shifting capability. For example, some designsherein have a head with 15% of the overall robot weight. Designs thatprovide battery capacity located in the robot sensor head and neck mayprovide head weight ranging as high as around 17%, 20%, or even 22% or25%, depending on CG shifting requirements and design constraints.Likewise, a lighter head can be employed if certain components likecameras or transmission gear are removed.

One embodiment of the robot depicted in FIG. 3 and FIG. 4 has thefollowing characteristics, preferred for CG shifting in certainscenarios.

TABLE 1 Weight Distribution for Design 1. Component: Component Weight:Percentage of overall wt: Chassis 21 lbs 70 Flippers 3 lbs 10 Head 4.5lbs 15 Neck 1.5 lbs  5 Payload 6 lbs (rating) Additional

The weights and ratios provided may vary slightly and still provide thedesired capabilities. Such embodiment also has physical parameters asfollows. Track wheel diameter of about 5 inches; chassis length about 17inches; flipper length about 9.5 inches; and neck length about 17inches. Such design provides ability to scale an obstacle in the forwarddirection having an 11.4 inch height. While these designs have beenprovided, size and weight ratios may change slightly and still providedthe desired climbing and maneuvering enhancements. The three designsherein have been configured to crest standard stair and obstacles in amanner such as depicted in FIGS. 18-21, for example, while stillmaintaining a robot that can stow flippers and neck to fold into asmall, man portable shape. For larger obstacles, the ratios given hereinmay be scaled appropriately and other ratios may be used successfullywith the CG shifting techniques taught herein.

Another embodiment of the robot depicted in FIG. 3 and FIG. 4 has thefollowing characteristics, preferred for CG shifting in certain otherscenarios.

TABLE 2 Weight Distribution for Design 2. Component: Component Weight:Percentage of overall wt: Chassis 19.5 lbs 65 Flippers 3 lbs 10 Head 4.5lbs 15 Neck 3 lbs 10 Payload 6 lbs (rating) Additional

This design has similar size parameters to the first listed design,Design 1. Because it is not desired to add “dead weight” or uselessweight, the additional neck weight is preferably a result of attachingpayloads to the neck or housing payloads inside the neck, as discussedabove. This may be desired, for example, to provide camera or RFsurveillance equipment, or other sensors, and recording transmissionelectronics that are spaced above the ground for optimum propagationcharacteristics. This configuration allows for CG shifting to enableaddressing obstacles of about 15.1 inches in one direction, and 11.6inches in both directions.

FIG. 5 depicts a side representation of another robot. In this robot,lightweight flippers 502 are provided on both ends of chassis 501.Preferably, the lightest feasible head 303 is assumed to offset theextra weight of the rear flippers 502. Chassis 501 is assumed to beslightly shorter than that in the previous embodiment since it is notneeded for stability and may be necessary to additionally offset moreweight for actuator and extra battery weight (due to added power drawfrom the extra flipper). Such design has a center of gravity (CG) at themark CG50 when resting in the depicted position. The added length due tothe extra flipper also provides a longer range of locations on whichpayloads can be mounted without overly shifting the vehicle CG.

TABLE 3 Weight Distribution for Design 3. Component: Component Weight:Percentage of overall wt: Chassis 22 lbs 73  Flippers 3 lbs 10 each setHead 1.2 lbs 4 Neck 0.9 lbs 3 Payload 6 lbs (rating) Additional

The preferred implementation of design 3 also has the following physicalparameters: wheel diameter, 5 inches; chassis length, 15 inches; flipperlength, 9.5 inches; and neck length, 15 inches. Such parameters provideability to scale a forward obstacle of 13.8 inches height when using theCO shifting techniques described herein.

While several design variations with different parameters are described,variations in size are accommodated for robots with different intendedpurposes. The designs included are intended to provide small robots thatare man-portable yet capable of climbing stairs. Larger robots, or othervehicles, may have little trouble climbing stairs, but may use the CGshifting techniques described herein to enable crossing crevasses,larger obstacles, or other purposes.

FIG. 6 depicts a robot vehicle encountering an obstacle under twodifferent scenarios. Regarding stairs and obstacles, the first step innegotiating any obstacle is to make sure the vehicle can transition upthe obstacle from a flat surface. For example, if the vehicle encountersa vertical wall but cannot at least get the front of the vehicle toclimb it, the vehicle typically will not be able to handle any obstaclesthat are more than one wheel radius. Preferably, the vehicle CG shouldbe as close to the rear axle as possible and the front of the vehicleshould encounter the obstacle as high as possible. On top of this, manyobstacles may be undercut such that the vehicle may wedge under it (suchas fire-escape stairs as depicted in FIG. 6 a), so having a very highapproach point is 5 important (large Y dimension). Also, note that suchobstacles result in a downward force being applied to the front of thevehicle unless there is some feature on the vehicle that can change thiscontact angle. It is for these reasons (among others) that the trackedvehicle robot systems preferably have flipper tracks on one end of thevehicle which can be rotated to any orientation, and that this isconsidered the “front” of the robot. This is depicted in FIG. 6 b. Forclarity, the end of the vehicle with flippers 602 attached is defined asthe “front,” but a vehicle may be run “backwards” to scale obstacles ifthis proves beneficial in some cases.

FIG. 7 depicts a robot vehicle having flippers residing within thelength of the vehicle. Such flippers greatly enhance the ability of asmall vehicle to scale large objects relative to it size. This is notonly due to the reasons above, but also because they increase thevehicle's footprint for a given stowed volume (since the flippers can befolded beside the vehicle when stowed, but can be deployed as necessaryfor a given obstacle). Flippers also are sometimes employed to right thevehicle when it is inverted. To do so, the vehicle CG must reside withinthe length of the flipper when it is stowed as shown in FIG. 7.

Assuming the chassis density is somewhat uniform (resulting in its CGbeing at its geometric center), and the flippers would shift the CGslightly off to the end to which they are mounted, this implies that theflippers typically not be shorter than about 50% of the chassis length.Therefore having the flippers be at least 50% of the chassis length is agood baseline unless the flippers are adapted to have more weight (inwhich case they could be slightly shorter).

It is also important for the flippers to spin 360 degrees continuouslyin either direction. This not only is necessary to recover from beinginverted, but it also considerably adds to the vehicle mobility oververy level and unstable terrain (such as 30 rocks or tall grass). Withsuch movement, the flippers may also act as arms to help pull thevehicle over such terrains.

Depending on what vehicle morphology is employed and where the averageCG location is located, the vehicle may be able to surmount larger,obstacles backwards than it can forwards. This happens when the vehicleCG is shifted aft and thus the lightweight flippers can be used toelevate the CG over the obstacle. By using the flippers to achieve“prairie-dog” pose (driving on the flipper tracks only), large obstaclescan be approached backwards as depicted in FIG. 8. The flippers are thenrotated to lift the front of the vehicle up to help scale the obstacle.

As described above, due to the limitations of the design in FIG. 8, anarticulated neck may also be added at the back of the robot. In suchembodiments, the neck may be moved to adjust the center of gravity (CG)of the robot and optimize obstacle scaling ability.

FIG. 9 shows and example of how a pivotable neck and sensor headcontribute significant CG shifting ability. A mobile robot's CGpreferably resides in a well-controlled range in order to negotiate awide array of obstacles. Further, a typical vehicle with a fixed CGwould need to have its CG near ground level and near the center of thetrack footprint. This, unfortunately, is difficult to achieve since itis difficult to design any “practical” system with the CG so far offsetfrom its volume centroid (most of the volume would need to remainvacant). This is especially true when ground clearance will need to beallotted on the bottom of the chassis.

The alternative to having a fixed CG is having some type of “CGshifting” capability such as that illustrated in FIG. 9. This means thatthe vehicle CG can be relocated as necessary to negotiate obstacles. Inthe illustrated example, the flippers 802 do allow for some CG shiftingsince they can be rotated in any direction and can be designed tocontain some percentage of the total weight of robot 800. However, sincethe flippers need to be in a defined position for many obstacles (andtherefore cannot be rotated at will), this limits their ability tocontribute adequate CG shifting ability. In contrast, the robot willoften be required to have a head that can be elevated via a neck thattypically has few constraints regarding its position while scalingobstacles (other than to give a remote operator ample viewing of thesurroundings).

The depicted robot 800 in FIG. 9 has a neck 805 that is a single, rigidlink. However, some embodiments may have necks with multiple links andarticulating joints or “elbows.” Neck 805 is illustrated in fivedifferent positions to illustrate its range of movement. Since the headis often required for scanning ability to have a high reach such as, forexample, at least 20 inches off of the ground, neck 805 is preferably aslong as possible while still stowable atop the robot 801 (represented byblack outline in FIG. 9). Having such a long neck 805 means that thehead 803 does not need to be a very large percentage of the robot weight(without payload) to result in fairly large CG shifts for the vehicle.In fact, the depiction above represents having only about 15% of therobot weight in the head, and another 5% in the neck itself. A longerneck is preferred for better leverage, so some robots have jointed necksor necks extending, in stowed positions, beyond the end of the chassis.

FIG. 9 depicts various target dots toward the center, each correspondingto a combined robot center of gravity for one position of the head. Thedepicted range of movement is exemplary, and other ranges of movementmay be achieved by placing neck 805 in other locations or changing theshape and design of neck 805, for example. Depicted position P1 producesa combined CG at the location marked CG1, thus lowering and movingforward the combined CG relative to most other positions. Depictedposition P2 produces a combined CG at the location marked CG2, which ishigher than CG1 and forward of most other positions. Depicted positionP3 produces a combined CG at the location marked CG3, this is thehighest depicted CG. Depicted position P4 produces a combined CG at thelocation marked CG4. Depicted position P5 is a stowed position, andproduces a combined CG at the location marked CG5, thus lowering andmoving forward the combined CG relative to most other positions. Thereare labeled dots also toward the center of the P4 head and neck, as wellas the flippers 802 and the chassis 801. These represent the individualcomponent center of gravity for that piece. Movement of the centers ofgravity of the head 803, neck 805, and flippers 802 effect the changesin combined CG position as described herein.

The depicted CG locations depend, of course, on the orientation of thevehicle. Climbing orientations with the chassis oriented at a pitch willof course have different CG locations, but the general CG shiftingeffect is exemplified in this drawing. CG locations also depend onflipper location and the relative weight of the flippers 802 to the restof robot 800.

In the depicted embodiment, though not visible in this siderepresentation, neck 805 is preferably adapted to move centrally betweenflippers 802 such that the flippers do not interfere with neck movement.Other positions may be used.

Note that the neck could be reversed from what is depicted above suchthat it pivots from the rear of the vehicle. This would shift thecentroid of the CG range aft, which can be advantageous if more weightis packaged in the flippers.

While CG shifting directed along the front/rear axis is depicted, CGshifting as described herein may of course be accomplished in otherdirections, such as sideways, or downward. For example, a robotnavigating a slope with a sideways slant may benefit from sideways ordiagonal CG shifting. Such shifting may be accomplished using varioushead/neck joint morphologies described herein.

FIG. 10 depicts elevated neck positions for two configurations. Thelocation of the neck pivot, whether mounted at the front or rear of thechassis, affects how high the head can be elevated off the ground forsurveillance. In both cases, the flippers can be 15 used to elevate thehead by either using “prairie-dog” (drive on flipper tracks only) or“bulldog” (run on the flipper tips and main tracks) poses. The formerresults in a higher head position as shown in FIG. 10.

Furthermore, it is possible to “combine” the chassis and the neck as asingle entity, and have dual flippers on one end of the vehicle. In thiscase, the vehicle always rides on one or both sets of lightweightflippers, and the heavy neck can be pivoted about the front axle tosupply the weight shifting ability. This concept requires longerflippers to effectively climb stairs, but has the benefit of having mostof its weight concentrated in the neck to achieve large CG shifts. Thehead (which would be at the end of the neck) could be elevated bystanding on the flipper tips to achieve the required height. Thisexample is described in a copending Patent Application No. 60/828,606,filed Oct. 6, 2006, and entitled “Robotic Vehicle.”

FIG. 11 depicts a robot 1100 in various positions crossing a crevasse.In operation, robot 1100 approaches the crevasse a (FIG. 11 a) with neck305 in a declined position that shifts the weight of the head and neckto move the robot's combined center of gravity (combined CG) to the spotmarked CG6. In this configuration, robot 1100 may move straight towardcrevasse A and roll forward until the front flipper contacts theopposing side of the crevasse. Because CG6 is never over the crevassebefore the leading flipper edge is supported, robot 1100 does not fall.

After reaching the position shown in FIG. 11A, the robot pivots neck 305to the second position depicted in FIG. 11B. In this position, the robotcombined CG is at the point marked CG7, which is over the chassisportions that are supported, and thereby robot 1100 may move forward andcomplete the crevasse crossing without the trailing end falling into thecrevasse. In a preferred embodiment, the robot can traverse frompositions 11A to 11B at the same time neck is moving to shift the robotCG, as long as neck gets to position 11B before robot does.

As shown, there are two distinct crevice dimensions, “A” and “B,”dictated by the location of the vehicle's CG relative to both of itsoutermost axles. Since any vehicle crossing a crevice must pass throughboth of these extremes, the maximum crevice that a vehicle can cross isalways the smaller of “A” or “B.” Note that for a typical vehicle with afixed CG location, the sum of A and B is always the total length of thetrack span. Therefore, the maximum crevice that a fixed-CG vehicle cancross can be no larger than half of the track span, and the CG mustreside in the middle of the track footprint to do so. However, if thevehicle is capable of shifting its CG fore and aft, it is possible tocross much larger crevices. In this case, the maximum crevice is stillthe smaller of A or B, but the sum and A and B is now equal to:A+B=Track Span+CG Shift

Since the maximum crevice would be when A=B, this gives:Maximum Crevice=(Track Span+CG Shift)/2

Therefore, the crevice size can be increased by half of whatever CGshifting ability can be achieved, but the vehicle's “average” CG shouldstill be in the middle of the track span or this gain is lost.

FIG. 12 depicts another robot CG shifting technique. Climbing stairsbecomes very difficult as vehicle size decreases. It is desired that thevehicle be stable at any point during climbing to allow stopping andstarting at any time and consistent performance at various speeds. Toclimb stairs stably, the vehicle CG must always be supported between twostep edges. This means that as the CG traverses over the edge of a step,the vehicle must be at least long enough to simultaneously span from thenext step edge to the previous step edge as shown below in FIG. 12. Thismeans that the total track footprint (the entire length of track incontact with the ground) must be at least two “step diagonals” long.

The depicted robot 1200 in FIG. 12 has neck 305 deployed in a stairascending position. Such position requires neck 305 to be pivotedforward such that the head and to neck center of gravities are in frontof the chassis. This provides, in the depicted scenario, a robotcombined CG located at the point marked CG9. Because this point is infront of the chassis contact with the middle stair when the rearmostchassis contact leaves the lower stair (forward motion), robot 1200 isstabilized. Some embodiments of robots may be so small that forwardstair climbing is not possible without such CG shifting. For example, asmall robot may have a combined CG at the point CG8, which would notprovide stable climbing because the rear end of the robot would sinkalong the lower step as forward progress is made, possibly even flippingover backwards. Such a robot, equipped with a head and neck as describedherein, may shift its CG up to position CG9 for example, and climbsuccessfully.

FIG. 13 is a flow chart of a method of ascending an obstacle. The methodis preferably employed with small robots having a neck and head asincluded herein, but may also be employed with larger robots or othervehicles. In Step 1301, the vehicle approaches the obstacle travelingforward and raises flippers (flippers are “front”). In step 1302, thevehicle mounts the obstacle preferably using its drive and flippertracks, to a position where the vehicle combined CG is either over thetop edge of the obstacle or maybe positioned thereby CG adjustment. Instep 1303, the vehicle pivots its neck to move the CG forward (towarddirection of motion) and preferably downward. In step 1304, flippers anddrives arc then used to complete the ascension. Various robots may beremotely controlled to perform the various navigational functionsdescribed herein, or they may be controlled by a programmed controller,preferably housed on the robot. A combination of such control methodsmay also be used.

FIG. 14 shows a robot 1400 having a wheel drive 1401. Wheels 1401 may beoverlapped to provide track-like maneuvering capability. They may alsobe provided with independent suspension. Wheels 1401 may be commonlydriven or independently driven. Robot 1400 may also perform the variousCG shifting functions described herein.

FIG. 15 depicts a robot in a stowed configuration. Neck 303 and head 305are stowed within the dimensions of chassis 301. Flippers 302 are alsopivoted back and stowed within the chassis 301. This configurationprovides a stowed length equal to the marked chassis length CL. That is,flipper length FL, neck length NL, and head length HL do not add to thecombined length of the robot in this stowed position. Further, theflippers, head, and neck in stowed position do not extend beyond thechassis height marked CH (or beyond the chassis width.) One preferredrobot design uses a CL of less than 24.5″, a CH of less than 7.5″, and achassis width of less than 16″.

FIG. 16 depicts a perspective view of another robot vehicle. FIG. 17depicts the robot of FIG. 16 in a climbing configuration. Referring toFIGS. 16 and. 17, the depicted robot vehicle has a chassis 1601 linkedto a track drive comprising wheels 1606 and track 1610. The front ofrobot 1600 is provide with flippers 1602 having tracks driven by wheels1600, which are linked to drive motors mounted on chassis 1601. Thedrive is preferably powered by power source 1608, which may be abattery, or other power source mounted to chassis 1601. The drive wheelsmaybe constructed according to techniques taught in U.S. Pat. No.6,615,885, which has been incorporated by reference herein.

The depicted robot 1600 has an articulated neck 1605, which may orienthead 1603 in various positions. FIG. 16 shows a typical maneuveringposition with the neck angled backward, moving the combined center ofgravity of robot further toward the rear end. This position may alsoallow viewing of flippers 1602 through visual sensors 1604. Bogierollers 1607 support track 1610. Such rollers may be in a single line ormay be staggered to provide more constant support for a track as itmoves along a stair edge, for example.

FIG. 17 depicts robot 1600 in a position that may improve climbingcapability. Flippers 1602 are deployed at a straight angle with thebottom of the chassis track drive. Neck 1605 is pivoted forward to movehead 1603 in front of the vehicle and thereby shift forward the vehiclecombined CG as described herein. Head 1603 is depicted rotated upon thefinal articulated portion of neck 1605, which may be employed to directsensors 1604 to varied directions. The depicted angle of neck 1605 isexemplary, and neck 1605 may be deployed at various angles includingbelow the angle of flippers 1602 in some implementations.

FIG. 18 depicts another robot in a stair climbing position with aforward-shifted combined CG. The depicted robot has chassis 801 having achassis CG marked toward its center. The robot is climbing a stairway.Flippers 802 are pivoted in a forward position along the stairway,having their lower track aligned with the bottom of the main drive trackof chassis 801. The combined CG is depicted as a large target dot. Thiscombined CG location is produced by orienting the flippers (having thedepicted flipper CG) as indicated and by moving neck 805 (having thedepicted neck CG) with head 803 (having the depicted head CG). The CGpositioned at this point allows smoother climbing as the rearmost trackcrests the depicted rearmost stair edge. The head is pivoted upward toallow sensors to view directly up the stairs.

FIG. 19 depicts another robot in a stair descending position. In thisconfiguration the robot has chassis 801 pointing downward. Neck 805 ispivoted back to move the combined CG (marked as “Combined CG”) to itsposition above the central depicted stair edge. Head 803 is pivoteddownward to view the path in front of the robot.

FIG. 20 depicts a robot climbing an obstacle forward. The depicted robotemploys 20 its flipper 802 track drives and chassis 801 drive to crestthe obstacle, then pivots forward flippers 802 and neck 805. Suchmovement shifts component weight to provide a combined CG at thedepicted point above the crest of the obstacle, which allows forwardmovement of the total robot mass on top of the obstacle.

FIG. 21 shows a robot mounting an obstacle backwards. The depicted robotpreferably approaches the obstacle in a manner depicted in FIG. 8. Neck805 and head 803 are then stowed to move the combined CG lower andtoward the desired direction of movement. This technique preferablyplaces the combined CG above the crest of the obstacle as indicated andmakes forward movement possible up the obstacle. FIG. 22 depicts acutaway perspective view of a robot 2200 according to anotherembodiment. The view highlights the morphology of moving joints alongthe robot's neck extension and sensor head. Each depicted axis allowsfor pivotal or panning movement about the central axis arrows depictedfor illustration only. Robot 2200 includes generally a right trackassembly 2202, a left track assembly 2204, and a head 2206, which areillustrated in dotted lines to show their position relative to thedepicted actuated joints or axes.

Specifically, the depicted robot also includes a shoulder axis oractuated joint 2208, a neck 2210, a first tilt axis or actuated joint2212, a pan axis or actuated joint 2214, and a second tilt axis oractuated joint 2216. Each depicted axis allows for pivotal or panningmovement about the central axis arrows depicted for illustration only.The depicted axes are actuated joints moveable by robotic actuatorscoupled thereto. A preferred joint or axis design includes an actuatormodule with a motor, a motor driver, and digital logic for motorcontrol. Axes employed herein may have variations of size, actuatorpower, and other parameters based on design considerations. For example,shoulder actuated joint or axis 2208 may be more powerful than the otherdepicted axes in some designs because of neck/head weight. Appropriategears may also couple the actuators to the attached moveable joints. Onepreferred actuator design scheme is further described below, but anysuitable actuators may be used.

Shoulder axis 2208 is mounted toward one end of the robot 2200 and isused to elevate the neck 2210. Preferably, actuated joint 2208 has amovement range limited only by the chassis of robot 2200. The movementrange thereby extends below parallel 20 toward both ends of robot 2200in a preferred design. Preferred actuator circuitry is further describedbelow. Toward the distal end of neck 2210, is first tilt axis 2212. Tiltaxis 2212 is, in this embodiment, parallel to shoulder axis 2208.Connected to one side of tilt axis 2212 is pan axis 2214, which is usedfor panning the head. Connected along the top of pan axis 2214 is thesecond tilt axis 2216. The depicted sensor head 2206 is fixed to the topof tilt axis 2216. Preferably, neck 2210 is constructed to provide alarge range of movement at each of the depicted axes.

FIG. 23 illustrates a cutaway perspective view of another robot 2300.The depicted view highlights the different neck-head axis topology. Eachdepicted axis allows for pivotal or panning movement about the centralaxis arrows depicted for illustration only. In this embodiment, therobot 2300 comprises right track assembly 2202, left track assembly2204, and head 2206. Robot 2300 also comprises shoulder axis 2208, neck2210, and first tilt axis 2212. The first tilt axis 2212 is attached toa pan link 2302. The pan link is also attached to the second tilt axis2216, and the second tilt axis 2216 is movably coupled to the head 2206.The pan link 2302 in general is an assembly with a panning axis and oneor more extended pieces which may include bends. A pan link may bepackaged into an assembly including a first piece perpendicular to neck2210, an actuator, and a second piece pivotable in a plane approximatelyparallel to neck 2210. (A preferred pan axis is further describedbelow). The depicted axes or “joints” are preferably implemented withactuators constructed as described herein. Various embodiments mayemploy different configurations to implement axes or joints depictedherein. As will be described further below, the pan link may beconstructed with a height that is approximately equivalent to the heightof a single actuator.

FIG. 24 depicts a cutaway perspective view of a robot 2500 according toanother embodiment. Each depicted axis allows for pivotal or panningmovement about the central axis arrows depicted for illustration only.The depicted axes are preferably implemented with actuators constructedas described herein. In this embodiment, robot 2500 comprises righttrack assembly 2202, left track assembly 2204, and head 2206. Robot 2500in this embodiment also includes shoulder axis 2208, neck 2210, firsttilt axis 2212, and tilt axis 2214. First tilt axis 2212 is movablyattached to tilt axis 2214, which is directly attached to head 2206.Panning capability provides the fourth degree of freedom of movement,and is enabled by twist joint 2502. An actuator providing joint movementfor twist joint 2502 may be provided in the interior of neck 2210 ormounted to the exterior. This variation provides four degrees of freedomfor movement while positioning three axes or actuated “joints” with ashort lever arm to move sensor head 2206.

FIG. 25 depicts another example of a robot 2500 in a perspective view.Each depicted axis allows for pivotal or panning movement about thecentral axis arrows depicted for illustration only. The depicted axesare preferably implemented with actuators constructed as describedherein. In this embodiment, robot 2600 includes right track assembly2202, left track assembly 2204, and head 2206. Robot 2500 also comprisesshoulder axis 2208, neck 2210, first tilt axis 2212, and pan axis 2214.In this embodiment, first tilt axis 2212 is mounted toward the distalend of neck 2210. A second tilt axis 2602 is connected to one side oftilt axis 2212. Tilt axis 2602 is connected to a piece of tilt axis 2212that is moveable with respect to neck 2210, and the second tilt axis issimilarly coupled to the pan axis 2214 to allow panning movement of head2206.

FIG. 26 depicts a perspective view of a robot 2600 according to anotherembodiment. Each depicted axis allows for pivotal or panning movementabout the central axis arrows depicted for illustration only. Thedepicted axes or “joints” are preferably implemented with actuatorsconstructed as described herein. In this embodiment, robot 2600 includesright track assembly 2202, left track assembly 2204, and head 2206.Robot 2600 also includes shoulder axis 2208, neck 2210, and first tiltaxis 2212 mounted toward the distal end of neck 2210. First tilt axis2212 is movably coupled by the actuator tilt action to a 45-degree linksection 2702. The 45-degree link section 2702 may be capable ofrotational motion about its length. Pan axis 2214 is fixed at the distalend of link section 2702, and head 2206 is thereby moveably mounted tothe top of pan axis 2214.

FIG. 27 illustrates a possible configuration of a preferred design for aneck extension and actuator assembly 4300 (“assembly 4300”) having a panaxis. Assembly 4300 comprises a shoulder actuated joint 4302, a neck4304, a first actuated tilt joint 4306, a actuated pan link 4308, and asecond actuated tilt joint 4310. The robot's sensor head is meant to bemounted atop the actuated tilt joint 4310. The depicted pan link designis a presently preferred embodiment of a pan link (FIG. 23). Shoulderactuated joint 4302 is coupled to neck 4304, and neck 4304 is coupled tofirst actuated tilt joint 4306. First actuated tilt joint 4306 ismovably coupled to pan link 4308. Pan link 4308 in this configuration ismovably coupled to actuated tilt joint 4310, and is capable of panningthe actuated tilt joint 4310. The depicted axes are preferablyimplemented with actuators constructed as described herein.

Actuated pan link 4308 provides further degrees of freedom head movementover other embodiments described herein with less than four degrees offreedom. The center of gravity shifting (CG shifting) techniquesdescribed herein may also be enhanced with use of pan link 4308.Specifically, the pan link may be pivoted or extended backward toachieve maximum rearward CG shifting described herein for tasks such asthe beginning phases of an obstacle climb. Similarly, actuated pan link4308 maybe pivoted forward and the head tilted down to achieve maximumforward-down CG shifting for tasks such as stair ascending andcompleting a large obstacle ascension, for example.

FIG. 28 illustrates a cutaway view of a possible embodiment of a roboticactuator assembly 4400 of FIG. 27. In this view, some of the outerhousings have been removed in order to reveal that the assembly 4400includes a shoulder axis actuator 4402, a first tilt axis actuator 4406,a pan link actuator 4408, and a second tilt axis actuator 4410. In thisview, it can also be seen that the assembly 4400 also includes ashoulder axis circuit board 4412, a neck circuit board 4414, a firsttilt axis circuit board 4416, a pan link circuit board 4418, and asecond tilt axis circuit board 4420. Each the circuit boards 4412through 4420 provide the circuit connectivity, power regulation, motioncontrol, sensors, and other functions related to each axis, and thecircuit boards 4412 through 4420 may be rigid circuit boards, flexiblepolyimide circuits, or other circuit modules or combinations thereof.

FIG. 29 depicts a cutaway view of a possible embodiment of a first tiltaxis 4500. In this view, the outer housing of the axis 4500 has beenremoved to reveal internal components that include circuit boards 4502,a motor 4504, a ring gear 4506, a pinion gear 4508, a output gear 4510,and a slip ring 4512. Circuit boards 4502 and slip ring 4512 may berigid circuit boards, flexible polyimide circuits, or other circuitmodules or combinations thereof, and may provide power regulation,motion control, sensors, and other functions related to the axis 4500.Motor 4504 is coupled to ring gear 4506, and ring gear 4506 ismechanically linked to pinion gear 4508 via a collection of planetarygears (hidden in this view). Ring gear 4506, pinion gear 4508, and thehidden planetary gears form a “planetary” gear system which transferspower from the motor 4504 to the output gear 4510 and provides a gearratio. Slip ring 4512 provides electrical connections that may conductpower, communications, and other signals.

FIG. 30 depicts another cutaway view of a possible embodiment of a firsttilt axis 4600. In this view, the outer housing and ring gear have beenremoved. In this view, circuit boards 4502, motor 4504, pinion gear4508, output gear 4510, and slip ring 4512 are all visible. In thisview, it can be seen that axis 4600 also includes a slip clutch 4602 anda collection of planet gear assemblies 4604. The depicted slip clutch4602 may help mitigate damage to the gears from outside pressurerotating the robot neck, for example. One preferred slip clutch designslips at about 400 inch-pounds of force. Other slip clutches may beused. The depicted motor actuator assembly is preferably backdriveable.Referring again to the actuated joints depicted in FIG. 27, actuatedtilt joint 4306, actuated pan joint 4308, an actuated tilt joint 4310,each employ backdriveable actuator motor in preferred embodiments.Preferably, the actuator modules employed in these three actuated jointsare interchangeable. That is the modules employed his same motor, gearedslip clutch, and gear electronics. In a preferred embodiment theactuated shoulder joint 4302 is non-backdriveable.

FIG. 31 depicts a cutaway view of a possible embodiment of a first tiltaxis 4700. This view has the outer housing and ring gear removed anddepicts circuit boards 4502, motor 4504, pinion gear 4508, and planetgear assemblies 4604. This view also has the slip clutch housing removedto reveal the clutch pack 4702. The clutch pack includes a collection ofclutch wafers and springs. While one slip clutch embodiment isdisclosed, other suitable clutches maybe employed depending on size,actuator design, performance requirements, and other design constraints.

FIG. 32 illustrates a cutaway view of a possible embodiment of a secondtilt axis 4800. This assembly includes an outer housing (removed in thisview), a ring gear (removed in this view), a motor 4802, a collection ofplanet gears 4804, a clutch pack 4806, and a sun gear 4808. The axis4800 also includes a slip ring 4810, and in this view half of the slipring has been hidden in order to reveal a collection of electricalcontacts 4812 that may conduct power, communications, and other signalsfrom the visible half of slip ring 4810 to the hidden half. Circuitboards 4810 and 4814 maybe rigid circuit boards, flexible polyimidecircuits, or other circuit modules or combinations thereof, and mayprovide power regulation, motion control, sensors, and other functionsrelated to the axis 4800.

FIG. 33 illustrates a cutaway view of a possible embodiment of a neckattachment or “shoulder” axis 4900. Various components have been hiddenin this view in order to reveal that the neck axis 4900 includes a slipring 4902. In this view, half of the slip ring has been hidden to revealthat the slip ring includes a collection of electrical contacts 4904that may conduct power, communications, and other signals from thehidden half to the visible half of slip ring 4902. Neck axis 4900 alsoincludes a spring 4906 mounted behind the slip ring 4902. This spring4906 may allow the slip ring to float, and this may allow the axis 4900to be constructed using greater mechanical tolerances than may otherwisebe allowed.

FIG. 34 depicts another cutaway view of a possible embodiment of a neckaxis 5000. Various components have been hidden in this view in order toreveal that the neck axis 5000 includes a first slip ring half 5002, asecond slip ring half 5004, and a collection of electrical contacts5006. Contacts 5006 maintain electrical contact with a collection ofconcentric electrical traces 5008. Slip ring components 5002 through5008 may be used to conduct power, communications, and other signals.First slip ring half 5002 and second slip ring half 5004 may beconstructed such that when the neck axis 5000 is disassembled, thehalves 5002 and 5004 separate. Such construction preferably allows awire free connection of robot neck and head. In certain embodiments, thefirst slip ring half 5002 and second slip ring half may be used as anabsolute encoder pair.

FIG. 35A and FIG. 35B show two exploded perspective views of a neckextension connector according to one embodiment. The depicted connectorbase 3502 is preferably mounted to chassis 301 on an interior-facingsurface such as an inside surface of the drive housing as depicted inseveral examples herein. The connector may of course be mounted in otherpositions such as a centrally located post or on an outer-facingsurface. The inner surface is preferred. Connector base 3502 is providedwith threads preferably arranged to provide a quarter-turn screw-onsequence for neck 3304. Base 3502 may be milled, machined, molded, ormanufactured with other suitable techniques. A preferred embodiment ismolded high-strength plastic, but other materials such as metals may beused. In a preferred embodiment connector base 35 at two is an engagingmount that has few threads. The threads have a very large pitch, andopen angle, and preferably no thread completes much more than a quarterperimeter. While quarter turn threads are taught, this is not limitingand other thread arrangements may be used. Preferably movement with lessthan half a rotation may assemble the opposing pieces of the connector.Interruptions may be provided along the perimeter between threads.

The neck connector piece 3512 is preferably a metal piece with interiorthreads adapted to screw onto the outer threads of base 3502. In someembodiments, connection may be made with a quarter turn engagement. Thatis, the neck or payload may be attached with a twist to engage thethreads on the base 3502 without a friction or interference fit. Such aconnection is secured with the use of a latch or other securing piece.Electrical contact pads 3504 are expressed on a circuit board which isfitted into base-3502. Contacts 3504 match to corresponding electricalcontacts 3522 (FIG. 35B) present inside the neck connector piece.Contacts 3522 are clocked to screw on and align with contacts 3504.Electrical connection is made through base 35 through pins projectingfrom the back of base 3502 to provide electrical conductivity into thechassis circuitry.

Referring to FIG. 35B, neck connector piece 3512 is attached to neck3304 via screwing or welding or other suitable technique, or neckconnector piece 3512 may be machined as part of the neck housing of neck3304. Neck connector piece 3512 has interior threads 3513. Behindthreads 3513 is a scaling o-ring or seal ring 3518. Seal ring 3518preferably forms a seal against base 3502 in the connector closedposition. Behind the seal ring 3518 is a small circuit board 3520 fitinto neck connector piece 3512. Preferably circuit board 3520 is sealedwith a second o-ring 3524. Contacts 3522 are, in this embodiment,mounted to circuit board 3520.

A latch 3506 is used to latch the depicted connector arrangement in aclosed position. Latch 3506 is shown with plunger 3508 spring loadedtherein. Plunger 3508 may be screwed into latch 3506 to adjust the latchclosing force. In preferred scenario the closing forces is adjustedsimilarly to a vice grips. That is plunger 3508 is screwed into latch3506 and the closing force tested until the latch can no longer beclosed. Then plunger 3508 is screwed out slightly to allow the latch toclose at its maximum closing force position. Such position provides, inpreferred embodiments, a zero-backlash connection. Latch 3506 isrotatably mounted to a latch base 3516 which in one embodiment isscrew-mounted to the chassis. In another embodiment the latch base maybe mounted to neck connector piece 3512.

FIG. 35C depicts the neck extension connector latched and secured. Theview is shown from the robot chassis side, with the robot chassis notshown in this cutaway view for clarity. After connection, the depictedconnector arrangement is secured by latch 3506. A plunger or screw 3508is moved into a matching hole or receiving slot 3526 on neck connectorpiece 3512 to secure the neck to the chassis. Such an arrangementprovides a mounting scenario with no tools, wires or screws, andprovides an adjustable latch which allows for different types ofpayloads to be mounted to connector 3502.

The depicted latch in a closed position provides a zero backlashconnection in that, once latched, the depicted neck connector has nofreedom of movement. The assembly may be referred to as a quick-connectzero backlash connector. Other suitable connector designs may beemployed to provide a quick connect zero backlash capability. Theplunger must be pulled out of receiving slot 3526 in order to disconnectthe connector. The unlatching movement is accomplished by pushing upwardon the head end of plunger 3508, thereby rotating latch base 3516 upwardabout screw 3528, while at the same time rotating the tip of plunger3508 downward along the surface of neck connector piece 3512 untilcontact is cleared. Assembly and disassembly are preferably accomplishedwith a single quarter turn movement and a latching or unlatchingmovement.

While the depicted connector is shown holding the robot neck assembly3304 onto the robot chassis, however such a connector maybe used as apayload connector to quick connect a variety of payloads to a robotchassis, or quick connect other robot pieces together while providing asealed housing and electrical connection as well as a zero backlashmechanical connection. Various payloads may be connected. For example acargo platform, or a manipulator arm may be connected. Various sensingpayloads or weapons payloads may also be connected.

FIG. 36 is a block diagram 28000 of one possible embodiment of a robothead 28002 (“head”, “robot head,” “sensor head”). The head 28002includes a head housing 28002 in which is mounted one or more circuitboards or circuit modules. Rigid circuit boards, flexible polyimidecircuits, multi-chip modules, or other circuit modules or combinationsmay be used. The depicted head 28002 has various cameras, sensors, andantenna mounted therein or thereto, and is typically itself mounted to arobot neck extension such as those described herein.

In this embodiment head 28002 includes a single board computer (SBC)28100, and in a preferred embodiment the SBC 28100 is a FreescaleMPC5200. Further, in one preferred embodiment the SBC is the controllerfor the entire robot. SBC 28100 is connected to a global positioningsystem (GPS) module 28102 by a serial bus, and in a preferred embodimentthe GPS 28102 is a uBlox Super Sense GPS module. The GPS module is alsoconnected to a GPS antenna 28108. The SBC 28100 also uses a PCI bus toconnect to a wireless Ethernet transceiver 28104 and afield-programmable gate array (FPGA) 28200. In a preferred embodiment,the FPGA 28200 is a Xilinx XC3S1000. SBC 28100 is electronicallyconnected to a first bus buffer 28105, which in a preferred embodimentis a Linear Technology LTC4304, which is connected to a PMBus 28604. Amicrocontroller power module 28106, which receives power from VSTBYpower 28107, is also connected to PMBus 28604 by a second bus buffer28108.

Referring now to the centrally depicted FPGA in FIG. 36, FPGA 28200 isprovided in robot head 28002 to perform various digital logic and datarouting functions such as multiplexing the video or sensor signals toappropriate destinations, as well as, in this embodiment, interfacing toan actuator data communications bus known as FARnet. FPGA 28200 iselectronically connected to control an LED power supply 28202, whichsupplies power to an infrared LED array 28204. FPGA 28200 iselectronically connected to a pair of RS485 transceivers 28206 and28208, and the transceivers 28206 and 28208 are connected to afour-conductor FARnet bus 28602. FPGA 28200 is also electronicallyconnected to a digital signal processor (DSP) 28400, which processesaudio signals that may be input from microphones or output to speakers.In one preferred embodiment, the DSP 28400 is a Texas InstrumentsTMS320DM642. DSP 28400 is electronically connected to an electronicmemory 28402, which may be RAM, SDRAM, flash, etc., or may be connectedto any combination of one or more of such types of memory. Preferably acombination of flash memory and SDRAM is employed for program and datastorage, and operating memory. DSP 28400 is electronically connected toan audio codec 28404, which in a preferred embodiment is a TexasInstruments TLV320A1C23, and the audio codec 28404 is connected to anaudio line input 28406, a microphone input 28408, a line output 28410,and an amplifier 28412.

The head 28000 also includes an electro-optic infrared (EOIR) module28900. EOIR 28900 includes a near infrared (NIR) camera 28902 (in apreferred embodiment, Sony 980), a long wave infrared (LWIR) camera anda laser range finder 28906. The EOIR cameras 28902 and 28904 areconnected to a pair of video decoders 28912 and 28914 (in a preferredembodiment, Analog Devices ADV7180). Laser range finder 28906 isconnected to a digital video input 28916. The video decoders 28912 and28914, the digital video input 28916, as well as a drive camera 28908are connected to FPGA 28200 by a CCIR-656 video communications bus and aserial bus. Video decoder 28914 is also connected to a differential NSTCreceiver 28918.

The depicted head 28000 also includes an Ethernet switch 28300 (in apreferred embodiment, Marvell 88E6063) which connects the SBC 28100 to ahead payload connector 28700, a head connector 28600 providingconnectivity to the robot base, and a local area network (LAN) radio28800. The Ethernet switch 28300 connections are made using a collectionof four-conductor Ethernet busses 28606. The LAN radio is connected to aLAN radio antenna 28806, a switch 28802, and a radio key 28804, whichmay be employed to enable certain functions on secure radios such asJTRS radios. The head 2800 includes a head latch control 28102, whichmay be operable to enable opening of the head housing or disconnectionfrom the neck.

Head connector 28600 connections for FARnet 28208, PMBus 28604, and 15Ethernet bus 28606. Head connector 28600 also includes a differentialNSTC signal conductor 28610 and a two-conductor power conductor 28608.Head payload connector 28700 includes connections for FARnet 28208,PMBus 28604, Ethernet bus 28606, and power conductor 28608. In thisembodiment, the power provided on conductors 28608 is converted by thefour depicted DC-DC converters, shown as 28004 through 28010. VSTBY isstandby voltage. The second depicted 3.3V out converter supplies thedigital logic such as the SBC 28100 (3.3V external) and audio codec28404. The third depicted converter supplies 5V output to as needed tocircuits such as the radio 28800 and sensors and cameras 28902, 28904,28906, and 28908. The fourth depicted converter 28010 supplies variousvoltages required to operate FPGA 28200 (3.3V).

FIG. 37 is a block diagram 2900 of one possible embodiment of a firsttilt module 2902. Tilt modules of this design may be used to implementthe various tilt axes employed in robots designs herein toward thedistal end of the robot's neck. Module 2902 houses one or more circuitboards or circuit modules. Rigid circuit boards, flexible polyimidecircuits, or other circuit modules or combinations may be used. Thedepicted module 2902 has various motors and sensors mounted therein orthereto, and is typically itself mounted to a robot neck extension suchas those described herein. Module 2902 may electrically connect to therobot head 28002 through electrical connections provided in a headconnector 2904, and these connections may include a four-conductorFARnet bus 2960, a four-conductor Ethernet bus 2964, a 2-conductor PMBus2966, a differential NSTC bus 2968, and 2-conductor power bus 2970.Busses 2960 through 2970 are also electrically connected to a slip ring2890. Power bus 2970 is electrically connected to DC-DC converters 2912and 2914, and these converters 2912 and 2914 provide power for theelectrical components included in first tilt module 2902.

An FPGA 2950 is provided in module 2902 to perform various digital logicand data routing functions such as multiplexing the video or sensorsignals to appropriate destinations, as well as, in this embodiment,interfacing to the actuator data communications bus known as FARnet. Ina preferred embodiment, FPGA 2950 is a XC3S500. FPGA 2950 is connectedto oscillator 2924, an EEPROM 2928, and RS485 transceivers 2926 and2930. Transceivers 2926 and 2930 are in communication with FARnet bus2960. The depicted FARnet busses are actuator control busses that, inone embodiment, are RS-485 serial busses. Their interconnection hereinforms a noded network of actuators. The FARnet bus scheme preferablyoperates as a noded scheme rather than detecting collisions on a commonbus, but a common bus scheme may be used. In this embodiment, each nodereceives commands, implements the commands addressed to itself, andforwards the other commands along the FARnet network.

Module 2902 also includes components used for motion control, such as apair of h-bridge drivers 2920 and 2922. Other motion control componentsincluded in the first tilt module 2902 include an h-bridge 2916, acurrent sense module 2918, an ADC 2932, a first tilt encoder 2934, andan encoder magnet 2936. The depicted encoders at each actuator hereinare preferably absolute position encoders rather than (or in conjunctionwith) differential encoders. Such encoders allow absolute positioncontrolling of the actuated joints. This scheme is advantageousespecially when combined with the slip clutches described herein whichmay prevent reliance on differential encoder tracking in somesituations. Other motion control components include a thermistor 2906, abrushless motor 2908, and a collection of hall sensors 2910.

FIG. 38 is a block diagram 3000 of one possible embodiment of a panmodule 3002. A pan module of this design may implement pan axes along arobot's neck according to various designs herein. The module 3002 housesone or more circuit boards or circuit modules. Rigid circuit boards,flexible polyimide circuits, or other circuit modules or combinationsmaybe used. The depicted module 3002 has various motors and sensorsmounted therein or thereto, and is typically itself mounted to a robotneck extension such as those described herein. Module 3002 mayelectrically connect to the robot head 2902 through electricalconnections provided in a slip ring 3080. Slip ring 3080 is preferablyelectrically coupled to slip ring 2980 (FIG. 37) with a passthroughconnector passing through the interior of the depicted upper curvedportion of pan link 4308 (FIG. 27). Such connections may include afour-conductor FARnet bus 3010, a four-conductor Ethernet bus 3036, a2-conductor PMBus 3038, a differential NSTC bus 3040, and 2-conductorpower bus 3042. Busses 3010, 3036, 3038, 3040, and 3042 are alsoelectrically connected to a slip ring 3050. Power bus 3042 iselectrically connected to DC-DC converters 3044 and 3046, and theseconverters 3044 and 3046 provide power for the electrical componentsincluded in pan module 3002.

Depicted in FIG. 38, an FPGA 3004 is provided in robot tilt module 3002to perform various digital logic and data routing functions such asmultiplexing the motion control or sensor signals to appropriatedestinations, as well as, in this embodiment, interfacing to theactuator data communications bus known as FARnet. In a preferredembodiment, FPGA 2950 is a XC3S500. FPGA 3004 is connected to oscillator3012, an EEPROM 3014, and RS485 transceivers 3006 and 3008. Transceivers3006 and 3008 are in communication with FARnet bus 3010.

Pan module 3002 also includes components used for motion control, suchas a pair of half bridge drivers 3016 and 3018. Other motion controlcomponents included in the pan module 3002 include an h-bridge 3022, acurrent sense module 3024, an ADC 3020, a pan encoder 3034, and anencoder magnet 3032. Other motion control components include athermistor 3026, a brushless motor 3028, and a collection of hallsensors 3030.

FIG. 39 is a block diagram 3100 of a robot lower neck assembly accordingto one embodiment. The assembly 3100 includes the entire lower neckassembly from the chassis or base attachment 3192 including shoulder or“collar” actuator 4302 (FIG. 27) and first tilt actuator 4306 (FIG. 27).In this embodiment, the assembly 3100 is represented as a combined lowerneck assembly module 3102 housing both shoulder actuator and first tiltactuator modules, shown together in this case because the depictedcircuits do not move with respect to each other. The lower neck assemblymodule 3102 includes one or more circuit boards or circuit modules andboth sets of actuator motors and gears. Rigid circuit boards, flexiblepolyimide circuits, or other circuit modules or combinations may beused. The depicted module 3102 has various motors and sensors mountedtherein or thereto, and is typically itself mounted to a robot neckextension such as those described herein. Module 3102 may electricallyconnect to the pan module 2902 through electrical connections providedin slip ring 3050. Such connections may include a four-conductor FARnetbus 3110, a four-conductor Ethernet bus 3150, a 2-conductor PMBus 3152,a differential NSTC bus 3155, and 2-conductor power bus 3154. Busses3150, 3152, and 3155 are also electrically connected to a collarconnector 3180. Power bus 3154 is electrically connected to DC-DCconverters 3162 and 3164, and these converters 3162 and 3164 providepower for the electrical components included in 15 shoulder tilt module3102. Power bus 3154 is also electrically connected to a linearregulator 3156 and a bus buffer 3158, and regulator 3156 and buffer 3158both electrically connect to a power module 3160.

Depicted toward the center of the block diagram in FIG. 39 is FPGA 3104,which is provided in module 3102 to perform various digital logic anddata routing functions such as multiplexing the motion control or sensorsignals to appropriate destinations, as well as, in this embodiment,interfacing to the actuator data communications bus known as FARnet. Ina preferred embodiment, FPGA 3104 is a XC3S500. FPGA 3104 is connectedto oscillator 3112, an EEPROM 3114, and RS485 transceivers 3106 and3108. Transceivers 3106 and 3108 are in communication with FARnet bus3110. FPGA 3104 and its associated transceivers perform as a singleFARnet node which receives control signals addressed to each of firsttilt module actuator motor 3138 and shoulder tilt module actuator motor3140.

Lower neck assembly module 3102 also includes components used for motioncontrol, such as four half bridge drivers 3116 through 3122. In apreferred embodiment, h-bridge drivers 3116 through 3122 are IntersilHIP2101. Other motion control components included in the module 3102include a pair of h-bridges 3126 and 3128, a pair of current sensemodules 3130 and 3132, an ADC 3124, a first tilt encoder 3168, a firsttilt encoder magnet 3116, a clavical encoder 3172, and a clavicalencoder magnet 3170. Other motion control components include a pair ofthermistors 3134 and 3136, a pair of brushless motors 3138 and 3140, anda collection of hall sensors 3142 and 3144. Electrical connection fromassembly 3102 to the robot base 3190 is made through a slip ring 3174and color connector 3180. Slip ring 3174 allows connectivity despiteactuator movement of the shoulder joint. The depicted collar connectors3180 and 3192 represent the connectors that join the neck to the chassis(FIGS. 35A-C).

FIG. 40 shows a block diagram 3200 for one possible embodiment of arobot chassis or base 3202. Preferably, base 3202 generally houses thepower supply (such as batteries) and much of the power control circuitryfor portable robot designs herein. The base 3202 may electricallyconnect to the robot neck at (module 3102) through electricalconnections provided in a collar connector 3250. Such connections mayinclude a first four-conductor FARnet bus 3208, a four-conductorEthernet bus 3222, a 2-conductor PM. Bus 3254, and a 2-conductor powerbus 3228.

Centrally located in FIG. 40, an FPGA 3204 is provided in the basecircuit 3202 to perform various digital logic and data routing functionssuch as multiplexing the motion control or sensor signals to appropriatedestinations, as well as, in this embodiment, interfacing to theactuator data communications bus known as FARnet. In a preferredembodiment, FPGA 3204 is a XC3S1000. FPGA 3204 is connected to a pair ofRS485 transceivers 3206. Transceivers 3206 are in communication withfirst FARnet bus 3208 and a second FARnet bus 3209.

Base 3202 also includes components used for motion control, such as anADC 3208, a flipper absolute encoder 3270, a flipper motor driver 3272,a drive1 motor driver and battery charger 3274, and a drive2 motordriver and battery charger 3276. Other motion control components includea set of three thermistors 3286, 3287, and 3288, a pair of BLDC motors3292 and 3293, a flipper brushless motor 3284, a set of threeincremental encoders 3280, 3281, and 3282, a brake 3291, and acollection of hall sensors 3289 and 3290.

Base 3202 also includes other various components used for power andcommunications, such as fiber connector 3212 which is opticallyconnected to fiber optic transceiver 3214 for connection of remotecontrol tethers. Transceiver 3214 converts the fiber optic basedcommunications to four-conductor electrical communications, and theEthernet bus that carries this converted communications is electricallyconnected to an Ethernet switch 3210. Ethernet switch 3210 is connectedto EEPROM 3216. Ethernet switch 3210 is in electrical communication witha maintenance port connector 3260, a collar connector 3250 via a firstisolation transformer 3220, and a payload connector A (3252) via asecond isolation transformer 3220. A collection of payload powerswitches 3226 electrically connects to collar connector 3250 via powerbus 3226, payload connector 3252 via a 2-conductor power bus 3256, and aset of power switches and ideal diodes 3242. Payload power switches 3226is also electrically connected to a power microcontroller 3238, which isalso connected to the power switches and ideal diodes 3242. The base3202 also includes a collection of power regulators and local controls3230 for controlling drive motors and other functions in base 3202, suchas flipper movement, for example. Payload connector 3252 also includeselectrical conductors for PM Bus 3254.

Visible in the left-central area of FIG. 32 is a 12C switch complexprogrammable logic device (CPLD) 3232. CPLD 3232 is electricallyconnected to a battery connector 1 3262 via opto-isolator 3234, and abattery connector 3264 via opto-isolator 3244.

FIG. 41 illustrates an embodiment of a robot 3300 that comprises a head3302, a neck 3304 in a stowed position, a pan link 3306 in an extendedposition, a set of flipper tracks 3308, and a set of drive tracks 3310.The robot is depicted in a low-profile pose. In this configuration, therobot 3300 is able to maintain a low overall profile while stillallowing the head 3302 to pan horizontally without colliding with anyother part of the robot 3300. This configuration may be useful forsituations such as inspecting the undersides of vehicles, buildings,inspecting culverts and other such confined spaces, roving underneathfences, and similar tasks. If a lower profile is required for roving,the pan link 3306 may be rotated into a stowed position in order to gainadditional clearance. Placing the pan link 3306 in a stowed position mayalso allow the robot 3300 to achieve a highly compact stowed positionfor storage and/or transport.

The depicted pose in FIG. 41 may be further described with reference tothe position of the various actuated joints shown in FIG. 27. Pursuantto independent commands propagated along the networks to the independentmotor modules, as shown in FIG. 41, actuated tilt joint 4302 rotatesitself to orient the neck flat or slightly elevated from flat. A flatbackward angle with respect to the chassis may be described as the baseor 0° position of actuated tilt joint 4302. Actuated tilt joint 4306rotates itself to orient 5 the pan link to a substantially 90° anglefrom neck 3304. Actuated pan joint 4308, to achieve the depicted pose,rotates itself to its 0° pan position, that is with the robot sensorface oriented toward the front of the robot. This pose allows, ofcourse, panning movement in pan axis 4308. Actuated tilt joint 4310rotates itself to its base or 0° tilt position, that is with thedepicted sensor face oriented at a 90° angle from the depicted verticalportion of pan link 3306.

FIG. 42 illustrates an example of robot 3300 in another possibleposition. In this configuration, the robot 3300 is largely horizontalwith the neck 3304 and head 3302 positioned in a largely verticalposition. Pan link 3306 may also be extended in order to achieveadditional height for the head 3302. This stance may be useful formaintaining a stable position while observing over obstacles, inspectingtabletops, observing though automobile windows, navigating throughvegetation, navigating through low-hanging fog or other gasses, etc.

To achieve the depicted pose, pursuant to independent commandspropagated along the network to the independent motor modules, flippers3308 orient themselves in an upright 90° position. Referring again tothe joints described in FIG. 27, actuated tilt joint 4302 rotates itselfto orient the neck at the 90° upright position. Actuated tilt joint 4306rotates itself to orient the pan link 3306 at a 0° parallel angle toneck 3304. Actuated pan joint 4308, if needed, rotates itself to its 0°pan position. Actuated tilt joint 2310 rotates itself to its 0° tiltposition.

FIG. 43 depicts robot 3300 in a possible position that may be suitablefor inspecting the entrance to a hole, cave, manhole, culvert, or othersuch opening that may be below the plane of the ground around it. Thisillustration shows that robot 3300 is capable of placing the neck in aposition such that the head is positioned below the plane of the drivetracks 3310. Pan link 3306 may also be extended to position the head3302 an additional distance below the ground plane. In the depictedposition, robot 3300 may be able to observe objects underneath thesurface that it is resting upon. With pan link 3306 extended downward,the robot 3300 is able to turn head 3302 and observe in severaldirections, for example, through a hole in a floor.

The depicted pose in FIG. 43 may be further described with reference tothe position of the various actuated joints shown in FIG. 27. Actuatedtilt joint 4302 rotates itself to orient the neck to an angle of about210° or greater. The depicted pose may require actuated tilt joint 4302to rotate to its greatest allow extent. Actuated tilt joint 4306 rotatesitself to orient the pan link to a substantially 30 to 45° angle fromneck 3304. Actuated tilt joint 4310 rotates itself to substantially 5 to10° forward of its base position. This angle may of course varydepending on whether the pose is looking into a hole, underneath abalcony, or inspecting the underside of its own supporting surface, forexample. A backward angle may be used to observe in a hole. A greaterangle around 15 to 30° would be needed to inspect the underside of itssupporting surface.

FIG. 44 depicts robot 3300 in a possible position where the neck 3304 isin a largely forward position and head 3302 is rotated to one side. Thisposition may be useful for observing around corners or other suchobstacles while keeping the rest of the robot 3300 protected or out ofview. In use, an operator may move the robot toward a corner until itdetects the stopping point, at a designated distance to present theextended neck beyond the corner. Then the operator commands the robot tomove to the depicted extended position for around-corner viewing.

The depicted pose in FIG. 44 may also be described with reference to theposition of the various actuated joints shown in FIG. 27. Actuated tiltjoint 4302 rotates itself to orient the neck, at substantially a 180° to190° angle from its 0° position. Actuated tilt joint 4306 rotates itselfto orient the pan link to substantially 0 to 10° backward angle fromneck 3304, needed to compensate for greater than 180° angle of neck.Actuated pan joint 4308, to achieve the depicted pose, rotates itself toa 90° right pan position. A pose for looking around corners to the leftwould of course be achieved by rotating actuated pan joint to a 90° leftposition.

FIG. 45 depicts robot 3300 in another possible position. In thisconfiguration, neck 3304, and pan link 3306 are tilted rearward and thesecond tilt axis 4310 (FIG. 27) is tilted forward so that the sensorface of head 3302 has a forward view. This position may achieve theminimum possible overall height for the robot 3300, and may be usefulfor inspecting the underside of vehicles, buildings, etc., fornavigating under or though passages that require low clearance, etc.

The depicted pose in FIG. 45 may also be described with reference to theposition of the various actuated joints shown in FIG. 27. Actuated tiltjoint 4302 rotates itself to orient the neck slightly elevated from theflat or 0° position, for example, about 5°. Actuated tilt joint 4306rotates itself to orient the pan link 3306 backward to a substantially15 to 20° angle from neck 3304. Actuated pan joint 4308 rotates itselfto its 0° pan position. Actuated tilt joint 4310 rotates itself as farforward of its 0° or upright position is possible without interferencewith pan link 3306, preferably up to a 90° forward rotation. This anglepreferably orient the sensor face close to parallel with the pan link3306.

FIG. 46 depicts robot 3300 in a position where neck 3304 is placed in alargely forward position, and the head 3302 is rotated such that thehead 3302 faces the robot 3300. This position may be useful forinspecting the front of the tracks or the underside of robot 3300,

The depicted pose in FIG. 46 may also be described with reference to theposition of the various actuated joints shown in FIG. 27. Actuated tiltjoint 4302 rotates itself to orient the neck at substantially a 180° to190° angle from its 0° position. Actuated tilt joint 4306 rotates itselfto orient the pan link to substantially 70 to 80° forward angle withrespect to the neck. Actuated pan joint 4308 rotates itself to its 0°pan position. Actuated tilt joint 4310 or take itself substantially 10°forward of its base position to orient a sensor face back toward a robotchassis. Preferably the movements of actuated tilt joints 4306 and 4310precede the final movement of actuated tilt joint 4302 to avoid thefloor interfering with head movement. Such coordinated movement may beprovided as a preprogrammed sequence to obtain a preset position which,like the other positions described herein, may be mapped to a remoteoperator control unit button or menu as a preset position.

FIG. 47 depicts robot 3300 in another possible position. In thisposition, neck 3304 is in a largely vertical position and head 3302 isin a downward-facing position. This stance may be useful for inspectingflipper tracks 3308, drive tracks 3310, or other parts of the robot3300.

The depicted pose in FIG. 47 may also be described with reference to theposition of the various actuated joints shown in FIG. 27. The depictedpose, like the others here shown herein, is preferably achieved pursuantto independent commands propagated along the network to the independentmotor modules. Referring again to the joints described in FIG. 27,actuated tilt joint 4302 rotates itself to orient the neck at the 90°upright position. Actuated tilt joint 4306 rotates itself to orient thepan link 3306 at a 0° parallel angle to neck 3304. Actuated pan joint4308, rotates itself to substantially a 90 to 100° right-hand panposition. Further panning may provide inspection of rearward portions ofthe right-hand track. Actuated tilt joint 2310 rotates itself tosubstantially a 45° downward tilt position from its 0° upright position.

FIG. 48 illustrates an example of robot 3300 in another possibleposition. The depicted robot 3300 is shown “standing” or orientedlargely vertically to elevate the sensor head as high as possible. Sucha pose may be useful for observation or radio transmission, for example.The depicted pose may be made leaning against a wall or other obstacle,or in some embodiments may be achieved with the use of rear flipperssuch as those disclosed above. The flipper angle to the wall shown isnot exclusive, and a much lower angle may be employ to more align theflippers with the robot chassis. To enter the depicted pose, the robot3300 may be navigated to contact a wall or other similar surface, andusing a set of flipper tracks 3308 the robot 3300 may “climb” up thewall in order to achieve a largely vertical stance. To begin theclimbing operation, the neck may be pivoted backward to a positionsubstantially 30° up from its flat, stowed position by actuated joint4302 (FIG. 27) to help alter the center of gravity for the robot 3300 inorder to enhance climbing capability. Preferably, as the chassis climbangle increases, the neck is pivoted upward to eventually reach itsdepicted angle.

The depicted pose in FIG. 48 may also be described with reference to theposition of the various actuated joints shown in FIG. 27. To achieve thedepicted pose, pursuant to independent commands propagated along thenetwork to the independent motor modules, flippers 3308 orientthemselves downward from a forward position parallel to the chassis.Depending on the obstacle and friction of the surface is involved theangle may be 30 anywhere from 0° to 90° forward rotation. Slightbackward rotation may also be used. Referring again to the jointsdescribed in FIG. 27, actuated tilt joint 4302 rotates itself to orientthe neck at substantially a 165-170° forward rotation, to orient theneck 3304 and substantially vertical position from the ground. Actuatedtilt joint 4306 rotates itself to orient the pan link 3306 at a 0°parallel angle to neck 3304. Actuated pan joint 4308 rotates itself toits 180° pan position. In the depicted pose, actuated pan joint 4308 mayrotated in all directions for observation. Actuated tilt joint 4310rotates itself to substantially its 0° tilt position.

FIG. 49 is an illustration that depicts robot 3300 in another possibleposition. In this example, the robot 3300 is largely horizontal, theneck 3304 is placed in a largely forward position, and the head is in anupward-facing position. This stance may be, useful for inspecting theundersides of objects, for peering upward from underneath an obstaclewith low clearance, and other similar tasks.

The depicted pose in FIG. 49 may also be described with reference to theposition of the various actuated joints shown in FIG. 27. Actuated tiltjoint 4302 rotates itself to orient the neck at substantially a 180 to190° angle from its 0° position. Actuated tilt joint 4306 rotates itselfto orient the pan link to substantially 100 to 115° backward angle fromneck 3304. Actuated pan joint 4308, to achieve the depicted pose,rotates itself to substantially a 0° forward pan position. Left andright panning motion may be employed in the depicted pose. Actuated tiltjoint 4310 rotates itself to substantially its 35 to 45° backward tiltposition.

FIG. 50 depicts a flow chart for moving to preset positions. Any of thepositions described herein, and other positions, may be set as presetconditions. Typically, a preset position may be selected by an operatoror an autonomous control program in response to operating conditions orscenarios. Preferably, an operator selects preset positions by selectinga preset button or combination, or selecting the position from a controlmenu as will be further described. In the depicted flow chart, robot3300 receives a present position command at its control computer in step4301. Such a command may also be generated by autonomous controlprograms running on the control computer or a remotely-located controlcomputer. The controller then transmits actuator control signals in step4302 to enter the preset position. In various embodiments such controlsignals may take various forms, such as absolute position commands toparticular actuators, or the controller may sense a present actuatorposition and issue relative commands. Such sensing may be left to localactuator control circuitry. The preset position commands may be sent tothe shoulder and neck actuators as described herein, but may also movethe robot flippers and tracks to certain present positions or movementscenarios. For example, a particular operator command may be present tocarry out a specific sequence such as an obstacle climbing sequenceinvolving a series of movements by one or more actuators as well astrack movements.

Preferably, actuator position commands are transmitted over a noddedactuator network such as the FARnet network described herein. Othersuitable control bus schemes may be used. In step 4303 the variousactuators move to their preset positions. Movement may be simultaneousor may be in a pre-designated order necessary to achieve a particulardesired movement sequence. For example, for the center of gravityshifting (CG-shifting) positions described herein, certain head and neckmovements may be needed in a particular position to achieve desiredCG-shifting movements appropriate for particular climbing sequences.

Other robotic vehicle details and features combinable with thosedescribed herein may be found in a U.S. Provisional application filedconcurrently herewith, entitled “Robotic Vehicle With Dynamic RangeActuators” and assigned Ser. No. 60/878,877, the entire contents ofwhich are hereby incorporated by reference for all purposes.

A number of embodiments of the invention have been described.Nevertheless, it will be understood that various modifications may bemade without departing from the spirit and scope of the invention. Forexample, various construction materials may be used. Further, othertechniques besides the depicted neck and head designs may be employed todo center of gravity shifting. Accordingly, other variations are withinthe scope of the following claims.

1. A method performed by a robot for addressing various obstacles, themethod comprising: assuming a stable stair ascending position, wherein:the robot comprises: a chassis having a chassis center of gravity; a setof driven flippers, each flipper having a proximal end, a distal end,and a flipper center of gravity therebetween, each the proximal end ofeach flipper coupled to the chassis near the leading end of the chassis;a neck having a pivot end, a distal end, and a neck center of gravitytherebetween, the neck pivotable about a second pivot axis substantiallyat the leading end of the chassis; and a sensor head at the distal endof the neck, the head having a pivot end, a distal end, and a headcenter of gravity therebetween, the head pivotable with respect to theneck about a third pivot axis at the distal end of the neck; and in thestable stair ascending position, the centers of gravity of the head,neck, and flippers are positioned to shift a vertical projection of theoverall center of gravity of the robot to at least one step span infront of the rearmost main track ground contact point and at least onestep span behind the foremost flipper track ground contact point; andassuming an unstable stair ascending position in which the centers ofgravity of the head, neck, and flippers are positioned to shift avertical projection of the overall center of gravity of the robot tooutside the stable range.
 2. The method of claim 1, further comprisingmoving the sensor head to point the sensor face to a right angle to theneck in an active position.
 3. The method of claim 1, further comprisingmoving the sensor head to point the sensor face approximately parallelto the neck in a stowed position.
 4. The method of claim 1, furthercomprising moving to one or more preset positions in response to arespective single operator command.
 5. The method of claim 1, whereinthe head houses at least part of a robot energy storage device.
 6. Themethod of claim 1, wherein a total weight of the robot is less thanabout 30 pounds, the sensor head comprises about 15 percent of a totalweight of the robot and the neck comprises about 5 percent of a totalweight of the robot.
 7. The method of claim 1, wherein the neckextension comprises one or more pass-through regions therein throughwhich one or more power cables are disposed, the one or more powercables providing power from batteries disposed on the chassis orsteerable drive to a controller in the sensor head.
 8. The method ofclaim 7, the robot further comprising a network switch disposed on thechassis, the network switch operably coupled to at least one networkcable connected to the sensor head from the chassis through the one ormore pass-through regions and operably coupling the network switch tothe controller.
 9. The method of claim 7, the robot further comprisingpower management circuitry disposed on the chassis and operably coupledto circuitry in the sensor head through a power management bus at leastpartially disposed in the pass-through regions.
 10. The method of claim3, wherein the neck includes an offset for receiving the head in linewith a portion of the neck in a stowed position in which the head andneck are substantially within a chassis profile.
 11. A method performedby a robot for ascending an obstacle, the method comprising: approachingthe obstacle by traveling in a forward direction towards a leading endof a chassis of the robot; raising a set of driven flippers coupled tothe chassis near the leading end of the chassis; mounting the obstacleusing a steerable drive supporting the chassis and the set of drivenflippers to a position where a robot combined CG is over a top edge ofthe obstacle; pivoting a neck extension and a pan link extension to movethe robot combined CG forward, the neck extension removably coupled tothe chassis by a neck connector, the pan link extension having proximaland distal ends being coupled to the neck extension at a proximal end ofthe neck extension with a first tilt access actuator, the pan linkextension having a sensor head coupled to a distal end of the pan linkextension; and completing the ascension by driving the steerable driveand the driven flippers.
 12. The method of claim 11, wherein pivotingthe neck extension and pan link extension to move the robot combined CGforward includes pivoting the neck extension and pan link extension tomove the robot combined CG downward.
 13. The method of claim 11, whereinthe pan link extension has a one axis actuator along its length.
 14. Themethod of claim 11, wherein the pan link extension has at least oneangled bend.
 15. The method of claim 11, wherein pivoting a neckextension and a pan link extension to move the robot combined CG forwardincludes pivoting the pan link extension about a first tilt axisactuator between the neck extension and the pan link extension.
 16. Themethod of claim 11, wherein pivoting a neck extension and a pan linkextension to move the robot combined CG forward includes moving thesensor head by pivoting the sensor head about a second tilt axis betweenthe sensor head and the pan link extension.
 17. The method of claim 16,further comprising rotating the second tilt axis actuator 360 degrees.